<?php

namespace SilverStripe\SQLite;

use SilverStripe\Assets\File;
use SilverStripe\Core\Config\Configurable;
use SilverStripe\Core\Convert;
use SilverStripe\Dev\Deprecation;
use SilverStripe\ORM\ArrayList;
use SilverStripe\ORM\Connect\Database;
use SilverStripe\ORM\DataList;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\PaginatedList;
use SilverStripe\ORM\Queries\SQLSelect;

/**
 * SQLite database controller class
 */
class SQLite3Database extends Database
{
    use Configurable;

    /**
     * Global environment config for setting 'path'
     */
    const ENV_PATH = 'SS_SQLITE_DATABASE_PATH';

    /**
     * Global environment config for setting 'key'
     */
    const ENV_KEY = 'SS_SQLITE_DATABASE_KEY';

    /**
     * Extension added to every database name
     *
     * @config
     * @var string
     */
    private static $database_extension = '.sqlite';

    /**
     * Database schema manager object
     *
     * @var SQLite3SchemaManager
     */
    protected $schemaManager = null;

    /*
     * This holds the parameters that the original connection was created with,
     * so we can switch back to it if necessary (used for unit tests)
     *
     * @var array
     */
    protected $parameters;

    /*
     * if we're on a In-Memory db
     *
     * @var boolean
     */
    protected $livesInMemory = false;

    /**
     * @var bool
     */
    protected $transactionNesting = 0;

    /**
     * List of default pragma values
     *
     * @todo Migrate to SS config
     *
     * @var array
     */
    public static $default_pragma = array(
        'encoding' => '"UTF-8"',
        'locking_mode' => 'NORMAL'
    );


    /**
     * Extension used to distinguish between sqllite database files and other files.
     * Required to handle multiple databases.
     *
     * @return string
     */
    public static function database_extension()
    {
        return static::config()->get('database_extension');
    }

    /**
     * Check if a database name has a valid extension
     *
     * @param string $name
     * @return boolean
     */
    public static function is_valid_database_name($name)
    {
        $extension = self::database_extension();
        if (empty($extension)) {
            return true;
        }

        return substr_compare($name, $extension, -strlen($extension), strlen($extension)) === 0;
    }

    /**
     * Connect to a SQLite3 database.
     * @param array $parameters An map of parameters, which should include:
     *  - database: The database to connect to, with the correct file extension (.sqlite)
     *  - path: the path to the SQLite3 database file
     *  - key: the encryption key (needs testing)
     *  - memory: use the faster In-Memory database for unit tests
     */
    public function connect($parameters)
    {
        if (!empty($parameters['memory'])) {
            Deprecation::notice(
                '1.4.0',
                "\$databaseConfig['memory'] is deprecated. Use \$databaseConfig['path'] = ':memory:' instead.",
                Deprecation::SCOPE_GLOBAL
            );
            unset($parameters['memory']);
            $parameters['path'] = ':memory:';
        }

        //We will store these connection parameters for use elsewhere (ie, unit tests)
        $this->parameters = $parameters;
        $this->schemaManager->flushCache();

        // Ensure database name is set
        if (empty($parameters['database'])) {
            $parameters['database'] = 'database';
        }
        // use the very lightspeed SQLite In-Memory feature for testing
        if ($this->getLivesInMemory()) {
            $file = ':memory:';
        } else {
            // Ensure path is given
            $path = $this->getPath();

            //assumes that the path to dbname will always be provided:
            $file = $path . '/' . $parameters['database'] . self::database_extension();
            if (!file_exists($path)) {
                SQLiteDatabaseConfigurationHelper::create_db_dir($path);
                SQLiteDatabaseConfigurationHelper::secure_db_dir($path);
            }
        }

        // 'path' and 'database' are merged into the full file path, which
        // is the format that connectors such as PDOConnector expect
        $parameters['filepath'] = $file;

        // Ensure that driver is available (required by PDO)
        if (empty($parameters['driver'])) {
            $parameters['driver'] = $this->getDatabaseServer();
        }

        $this->connector->connect($parameters, true);

        foreach (self::$default_pragma as $pragma => $value) {
            $this->setPragma($pragma, $value);
        }

        if (empty(self::$default_pragma['locking_mode'])) {
            self::$default_pragma['locking_mode'] = $this->getPragma('locking_mode');
        }
    }

    /**
     * Retrieve parameters used to connect to this SQLLite database
     *
     * @return array
     */
    public function getParameters()
    {
        return $this->parameters;
    }

    /**
     * Determine if this Db is in memory
     *
     * @return bool
     */
    public function getLivesInMemory()
    {
        return isset($this->parameters['path']) && $this->parameters['path'] === ':memory:';
    }

    /**
     * Get file path. If in memory this is null
     *
     * @return string|null
     */
    public function getPath()
    {
        if ($this->getLivesInMemory()) {
            return null;
        }
        if (empty($this->parameters['path'])) {
            return ASSETS_PATH . '/.sqlitedb';
        }
        return $this->parameters['path'];
    }

    public function supportsCollations()
    {
        return true;
    }

    public function supportsTimezoneOverride()
    {
        return false;
    }

    /**
     * Execute PRAGMA commands.
     *
     * @param string $pragma name
     * @param string $value to set
     */
    public function setPragma($pragma, $value)
    {
        $this->query("PRAGMA $pragma = $value");
    }

    /**
     * Gets pragma value.
     *
     * @param string $pragma name
     * @return string the pragma value
     */
    public function getPragma($pragma)
    {
        return $this->query("PRAGMA $pragma")->value();
    }

    public function getDatabaseServer()
    {
        return "sqlite";
    }

    public function selectDatabase($name, $create = false, $errorLevel = E_USER_ERROR)
    {
        if (!$this->schemaManager->databaseExists($name)) {
            // Check DB creation permisson
            if (!$create) {
                if ($errorLevel !== false) {
                    user_error("Attempted to connect to non-existing database \"$name\"", $errorLevel);
                }
                // Unselect database
                $this->connector->unloadDatabase();
                return false;
            }
            $this->schemaManager->createDatabase($name);
        }

        // Reconnect using the existing parameters
        $parameters = $this->parameters;
        $parameters['database'] = $name;
        $this->connect($parameters);
        return true;
    }

    public function now()
    {
        return "datetime('now', 'localtime')";
    }

    public function random()
    {
        return 'random()';
    }

    /**
     * The core search engine configuration.
     * @todo There is a fulltext search for SQLite making use of virtual tables, the fts3 extension and the
     * MATCH operator
     * there are a few issues with fts:
     * - shared cached lock doesn't allow to create virtual tables on versions prior to 3.6.17
     * - there must not be more than one MATCH operator per statement
     * - the fts3 extension needs to be available
     * for now we use the MySQL implementation with the MATCH()AGAINST() uglily replaced with LIKE
     *
     * @param array $classesToSearch
     * @param string $keywords Keywords as a space separated string
     * @param int $start
     * @param int $pageLength
     * @param string $sortBy
     * @param string $extraFilter
     * @param bool $booleanSearch
     * @param string $alternativeFileFilter
     * @param bool $invertedMatch
     * @return PaginatedList DataObjectSet of result pages
     */
    public function searchEngine(
        $classesToSearch,
        $keywords,
        $start,
        $pageLength,
        $sortBy = "Relevance DESC",
        $extraFilter = "",
        $booleanSearch = false,
        $alternativeFileFilter = "",
        $invertedMatch = false
    ) {
        $start = (int)$start;
        $pageLength = (int)$pageLength;
        $keywords = $this->escapeString(str_replace(array('*', '+', '-', '"', '\''), '', $keywords));
        $htmlEntityKeywords = htmlentities(utf8_decode($keywords));

        $pageClass = 'SilverStripe\\CMS\\Model\\SiteTree';
        $fileClass = 'SilverStripe\\Assets\\File';

        $extraFilters = array($pageClass => '', $fileClass => '');

        if ($extraFilter) {
            $extraFilters[$pageClass] = " AND $extraFilter";

            if ($alternativeFileFilter) {
                $extraFilters[$fileClass] = " AND $alternativeFileFilter";
            } else {
                $extraFilters[$fileClass] = $extraFilters[$pageClass];
            }
        }

        // Always ensure that only pages with ShowInSearch = 1 can be searched
        $extraFilters[$pageClass] .= ' AND ShowInSearch <> 0';
        // File.ShowInSearch was added later, keep the database driver backwards compatible
        // by checking for its existence first
        if (File::singleton()->getSchema()->fieldSpec(File::class, 'ShowInSearch')) {
            $extraFilters[$fileClass] .= " AND ShowInSearch <> 0";
        }

        $limit = $start . ", " . $pageLength;

        $notMatch = $invertedMatch ? "NOT " : "";
        if ($keywords) {
            $match[$pageClass] =
                "(Title LIKE '%$keywords%' OR MenuTitle LIKE '%$keywords%' OR Content LIKE '%$keywords%'"
                . " OR MetaDescription LIKE '%$keywords%' OR Title LIKE '%$htmlEntityKeywords%'"
                . " OR MenuTitle LIKE '%$htmlEntityKeywords%' OR Content LIKE '%$htmlEntityKeywords%'"
                . " OR MetaDescription LIKE '%$htmlEntityKeywords%')";
            $fileClassSQL = Convert::raw2sql($fileClass);
            $match[$fileClass] =
                "(Name LIKE '%$keywords%' OR Title LIKE '%$keywords%') AND ClassName = '$fileClassSQL'";

            // We make the relevance search by converting a boolean mode search into a normal one
            $relevanceKeywords = $keywords;
            $htmlEntityRelevanceKeywords = $htmlEntityKeywords;
            $relevance[$pageClass] =
                "(Title LIKE '%$relevanceKeywords%' OR MenuTitle LIKE '%$relevanceKeywords%'"
                . " OR Content LIKE '%$relevanceKeywords%' OR MetaDescription LIKE '%$relevanceKeywords%')"
                . " + (Title LIKE '%$htmlEntityRelevanceKeywords%' OR MenuTitle LIKE '%$htmlEntityRelevanceKeywords%'"
                . " OR Content LIKE '%$htmlEntityRelevanceKeywords%' OR MetaDescription "
                . " LIKE '%$htmlEntityRelevanceKeywords%')";
            $relevance[$fileClass] = "(Name LIKE '%$relevanceKeywords%' OR Title LIKE '%$relevanceKeywords%')";
        } else {
            $relevance[$pageClass] = $relevance[$fileClass] = 1;
            $match[$pageClass] = $match[$fileClass] = "1 = 1";
        }

        // Generate initial queries
        $queries = array();
        foreach ($classesToSearch as $class) {
            $queries[$class] = DataList::create($class)
                ->where($notMatch . $match[$class] . $extraFilters[$class])
                ->dataQuery()
                ->query();
        }

        // Make column selection lists
        $select = array(
            $pageClass => array(
                "\"ClassName\"",
                "\"ID\"",
                "\"ParentID\"",
                "\"Title\"",
                "\"URLSegment\"",
                "\"Content\"",
                "\"LastEdited\"",
                "\"Created\"",
                "NULL AS \"Name\"",
                "\"CanViewType\"",
                $relevance[$pageClass] . " AS Relevance"
            ),
            $fileClass => array(
                "\"ClassName\"",
                "\"ID\"",
                "NULL AS \"ParentID\"",
                "\"Title\"",
                "NULL AS \"URLSegment\"",
                "NULL AS \"Content\"",
                "\"LastEdited\"",
                "\"Created\"",
                "\"Name\"",
                "NULL AS \"CanViewType\"",
                $relevance[$fileClass] . " AS Relevance"
            )
        );

        // Process queries
        foreach ($classesToSearch as $class) {
            // There's no need to do all that joining
            $queries[$class]->setFrom('"'.DataObject::getSchema()->baseDataTable($class).'"');
            $queries[$class]->setSelect(array());
            foreach ($select[$class] as $clause) {
                if (preg_match('/^(.*) +AS +"?([^"]*)"?/i', $clause, $matches)) {
                    $queries[$class]->selectField($matches[1], $matches[2]);
                } else {
                    $queries[$class]->selectField(str_replace('"', '', $clause));
                }
            }

            $queries[$class]->setOrderBy(array());
        }

        // Combine queries
        $querySQLs = array();
        $queryParameters = array();
        $totalCount = 0;
        foreach ($queries as $query) {
            /** @var SQLSelect $query */
            $querySQLs[] = $query->sql($parameters);
            $queryParameters = array_merge($queryParameters, $parameters);
            $totalCount += $query->unlimitedRowCount();
        }

        $fullQuery = implode(" UNION ", $querySQLs) . " ORDER BY $sortBy LIMIT $limit";
        // Get records
        $records = $this->preparedQuery($fullQuery, $queryParameters);

        foreach ($records as $record) {
            $objects[] = new $record['ClassName']($record);
        }

        if (isset($objects)) {
            $doSet = new ArrayList($objects);
        } else {
            $doSet = new ArrayList();
        }
        $list = new PaginatedList($doSet);
        $list->setPageStart($start);
        $list->setPageLength($pageLength);
        $list->setTotalItems($totalCount);
        return $list;
    }

    /*
     * Does this database support transactions?
     */
    public function supportsTransactions()
    {
        return version_compare($this->getVersion(), '3.6', '>=');
    }

    public function supportsExtensions($extensions = array('partitions', 'tablespaces', 'clustering'))
    {
        if (isset($extensions['partitions'])) {
            return true;
        } elseif (isset($extensions['tablespaces'])) {
            return true;
        } elseif (isset($extensions['clustering'])) {
            return true;
        } else {
            return false;
        }
    }

    public function transactionStart($transaction_mode = false, $session_characteristics = false)
    {
        if ($this->transactionNesting > 0) {
            $this->transactionSavepoint('NESTEDTRANSACTION' . $this->transactionNesting);
        } else {
            $this->query('BEGIN');
        }
        ++$this->transactionNesting;
    }

    public function transactionSavepoint($savepoint)
    {
        $this->query("SAVEPOINT \"$savepoint\"");
    }

    public function transactionRollback($savepoint = false)
    {
        // Named transaction
        if ($savepoint) {
            $this->query("ROLLBACK TO $savepoint;");
            return true;
        }

        // Fail if transaction isn't available
        if (!$this->transactionNesting) {
            return false;
        }

        --$this->transactionNesting;
        if ($this->transactionNesting > 0) {
            $this->transactionRollback('NESTEDTRANSACTION' . $this->transactionNesting);
        } else {
            $this->query('ROLLBACK;');
        }
        return true;
    }

    public function transactionDepth()
    {
        return $this->transactionNesting;
    }

    public function transactionEnd($chain = false)
    {
        // Fail if transaction isn't available
        if (!$this->transactionNesting) {
            return false;
        }
        --$this->transactionNesting;
        if ($this->transactionNesting <= 0) {
            $this->transactionNesting = 0;
            $this->query('COMMIT;');
        }
        return true;
    }

    /**
     * In error condition, set transactionNesting to zero
     */
    protected function resetTransactionNesting()
    {
        $this->transactionNesting = 0;
    }

    public function query($sql, $errorLevel = E_USER_ERROR)
    {
        $this->inspectQuery($sql);
        return parent::query($sql, $errorLevel);
    }

    public function preparedQuery($sql, $parameters, $errorLevel = E_USER_ERROR)
    {
        $this->inspectQuery($sql);
        return parent::preparedQuery($sql, $parameters, $errorLevel);
    }

    /**
     * Inspect a SQL query prior to execution
     *
     * @param string $sql
     */
    protected function inspectQuery($sql)
    {
        // Any DDL discards transactions.
        $isDDL = $this->getConnector()->isQueryDDL($sql);
        if ($isDDL) {
            $this->resetTransactionNesting();
        }
    }

    public function clearTable($table)
    {
        $this->query("DELETE FROM \"$table\"");
    }

    public function comparisonClause(
        $field,
        $value,
        $exact = false,
        $negate = false,
        $caseSensitive = null,
        $parameterised = false
    ) {
        if ($exact && !$caseSensitive) {
            $comp = ($negate) ? '!=' : '=';
        } else {
            if ($caseSensitive) {
                // GLOB uses asterisks as wildcards.
                // Replace them in search string, without replacing escaped percetage signs.
                $comp = 'GLOB';
                $value = preg_replace('/^%([^\\\\])/', '*$1', $value);
                $value = preg_replace('/([^\\\\])%$/', '$1*', $value);
                $value = preg_replace('/([^\\\\])%/', '$1*', $value);
            } else {
                $comp = 'LIKE';
            }
            if ($negate) {
                $comp = 'NOT ' . $comp;
            }
        }

        if ($parameterised) {
            return sprintf("%s %s ?", $field, $comp);
        } else {
            return sprintf("%s %s '%s'", $field, $comp, $value);
        }
    }

    public function formattedDatetimeClause($date, $format)
    {
        preg_match_all('/%(.)/', $format, $matches);
        foreach ($matches[1] as $match) {
            if (array_search($match, array('Y', 'm', 'd', 'H', 'i', 's', 'U')) === false) {
                user_error('formattedDatetimeClause(): unsupported format character %' . $match, E_USER_WARNING);
            }
        }

        $translate = array(
            '/%i/' => '%M',
            '/%s/' => '%S',
            '/%U/' => '%s',
        );
        $format = preg_replace(array_keys($translate), array_values($translate), $format);

        $modifiers = array();
        if ($format == '%s' && $date != 'now') {
            $modifiers[] = 'utc';
        }
        if ($format != '%s' && $date == 'now') {
            $modifiers[] = 'localtime';
        }

        if (preg_match('/^now$/i', $date)) {
            $date = "'now'";
        } elseif (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
            $date = "'$date'";
        }

        $modifier = empty($modifiers) ? '' : ", '" . implode("', '", $modifiers) . "'";
        return "strftime('$format', $date$modifier)";
    }

    public function datetimeIntervalClause($date, $interval)
    {
        $modifiers = array();
        if ($date == 'now') {
            $modifiers[] = 'localtime';
        }

        if (preg_match('/^now$/i', $date)) {
            $date = "'now'";
        } elseif (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
            $date = "'$date'";
        }

        $modifier = empty($modifiers) ? '' : ", '" . implode("', '", $modifiers) . "'";
        return "datetime($date$modifier, '$interval')";
    }

    public function datetimeDifferenceClause($date1, $date2)
    {
        $modifiers1 = array();
        $modifiers2 = array();

        if ($date1 == 'now') {
            $modifiers1[] = 'localtime';
        }
        if ($date2 == 'now') {
            $modifiers2[] = 'localtime';
        }

        if (preg_match('/^now$/i', $date1)) {
            $date1 = "'now'";
        } elseif (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date1)) {
            $date1 = "'$date1'";
        }

        if (preg_match('/^now$/i', $date2)) {
            $date2 = "'now'";
        } elseif (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date2)) {
            $date2 = "'$date2'";
        }

        $modifier1 = empty($modifiers1) ? '' : ", '" . implode("', '", $modifiers1) . "'";
        $modifier2 = empty($modifiers2) ? '' : ", '" . implode("', '", $modifiers2) . "'";

        return "strftime('%s', $date1$modifier1) - strftime('%s', $date2$modifier2)";
    }
}